Hi everyone, original poster here. I managed to get the code down to less than 5000 characters including the extra config changes that the Shopify buy button offered. This includes colour changes, quantity box, and font changes.
Please feel free to copy my code and change any of the above settings where you see fit. If you go on http://jsbeautifier.org/ you can see it clearer
<script data-shopify-buy-ui> (function(){var scriptURL='https://sdks.shopifycdn.com/buy-button/latest/buy-button-storefront.min.js'; if (window.ShopifyBuy){if (window.ShopifyBuy.UI){ShopifyBuyInit();}else{loadScript();}}else{loadScript();}function loadScript(){var script=document.createElement('script'); script.async=true; script.src=scriptURL; (document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(script); script.onload=ShopifyBuyInit;}function ShopifyBuyInit(){var client=ShopifyBuy.buildClient({domain: 'smith-and-sinclair.myshopify.com', apiKey: '54e8e901a1c06b0d398baaad2b6e5e7f', appId: '6',}); ShopifyBuy.UI.onReady(client).then(function(ui){ui.createComponent('product',{id: [7676391559], moneyFormat: '£{{amount}}', options:{"product":{"buttonDestination": "cart", "layout": "vertical", "variantId": "all", "width": "240px","font-weight": "bold", "contents":{"img": false, "title": false, "variantTitle": false, "options": true, "price": false, "description": false, "buttonWithQuantity": true, "button": false, "quantity": false}, "text":{"button": "Add to basket"}, "styles":{"product":{"@media (min-width: 601px)":{"max-width": "100%", "margin-left": "0", "margin-bottom": "50px"}}, "button":{"font-family": "Roboto, sans-serif", "background-color": "#0f1f3c", "color": "#ffffff", "font-size": "13px", "padding-top": "14.5px", "padding-bottom": "14.5px", "padding-left": "14px", "padding-right": "14px", ":hover":{"background-color": "#1a3566", "color": "#ffffff"}, "border-radius": "5px", ":focus":{"background-color": "#1a3566"}, "font-weight": "bold"}, "quantityInput":{"font-size": "13px", "padding-top": "14.5px", "padding-bottom": "14.5px", "color": "#4c4c4c"}, "compareAt":{"font-size": "12px"}}, "googleFonts": ["Roboto"]}, "cart":{"contents":{"title": true, "lineItems": true, "footer": true, "button": true}, "text":{"title": "Basket", "total": "Total", "notice": "Shipping and discount codes are added at checkout.", "button": "CHECKOUT"}, "styles":{"button":{"background-color": "#0f1f3c", "color": "#ffffff", "font-family": "Roboto, sans-serif", "font-size": "13px", "padding-top": "14.5px", "padding-bottom": "14.5px", "padding-left": "26px", "padding-right": "26px", "border": "none", ":hover":{"background-color": "#1a3566", "color": "#ffffff"}, "border-radius": "5px", ":focus":{"background-color": "#1a3566"}, "font-weight": "bold"}, "cart":{"background-color": "#ffffff"}, "footer":{"background-color": "#ffffff"}}, "googleFonts": ["Roboto"]}, "modalProduct":{"contents":{"img": true, "title": true, "variantTitle": false, "options": true, "price": true, "description": true, "buttonWithQuantity": false, "button": true, "quantity": false}, "text":{"button": "ADD TO CART"}, "styles":{"product":{"@media (min-width: 601px)":{"max-width": "100%", "margin-left": "20px", "margin-bottom": "50px"}}, "button":{"background-color": "#0f1f3c", "color": "#ffffff", "font-family": "Roboto, sans-serif", "font-size": "13px", "padding-top": "14.5px", "padding-bottom": "14.5px", "padding-left": "14px", "padding-right": "14px", "border": "none", ":hover":{"background-color": "#1a3566", "color": "#ffffff"}, "border-radius": "5px", ":focus":{"background-color": "#1a3566"}, "font-weight": "bold"}, "variantTitle":{"font-family": "Roboto, sans-serif", "font-size": "14px", "color": "#4c4c4c", "font-weight": "bold"}, "title":{"font-family": "Roboto, sans-serif", "font-weight": "bold", "font-size": "26px", "color": "#4c4c4c"}, "description":{"color": "#4c4c4c", "font-size": "14px", "font-family": "Roboto, sans-serif", "font-weight": "bold"}, "price":{"font-family": "Roboto, sans-serif", "font-size": "14px", "color": "#4c4c4c", "font-weight": "bold"}, "quantityInput":{"font-size": "13px", "padding-top": "14.5px", "padding-bottom": "14.5px", "color": "#4c4c4c"}, "compareAt":{"font-family": "Roboto, sans-serif", "font-weight": "bold"}}, "googleFonts": ["Roboto", "Roboto", "Roboto", "Roboto", "Roboto", "Roboto"]}, "productSet":{"styles":{"products":{"@media (min-width: 601px)":{"margin-left": "-20px"}}}}, "toggle":{"styles":{"toggle":{"font-family": "Roboto, sans-serif", "background-color": "#0f1f3c", ":hover":{"background-color": "#1a3566"}, ":focus":{"background-color": "#1a3566"}, "font-weight": "bold"}, "count":{"color": "#ffffff", ":hover":{"color": "#ffffff"}, "font-size": "13px"}, "iconPath":{"fill": "#ffffff"}}, "googleFonts": ["Roboto"]}, "modal":{"styles":{"modal":{"background-color": "#ffffff"}}}, "option":{"styles":{"label":{"font-family": "Roboto, sans-serif", "font-weight": "bold", "color": "#4c4c4c"}, "select":{"font-family": "Roboto, sans-serif", "font-weight": "bold", "color": "#4c4c4c"}}, "googleFonts": ["Roboto"]}}});});}})();</script>
Hope this helps!
I also agree with increasing the character limit though would solve many problems!