Am I allowed to sell on Amazon but goods are sent to customer via Drop Ship from a Alibaba supplier?

Drop-shipping is inadvisable, but not fully against Amazon policy… https://sellercentral-europe.amazon.com/help/hub/reference/G201808410

Drop shipping, or allowing a third-party to fulfill orders to customers on your behalf, is not acceptable unless it is clear to the customer that you are the seller of record. The following examples of drop shipping are policy violations that may result in a restriction of your ability to sell using Amazon’s Merchant Fulfilled Network (MFN):

• Purchasing products from another online retailer and having that retailer ship directly to customers, if the shipment does not identify you as the seller of record or if anyone other than you (including the other online retailer) appears on packing slips, invoices, or external packaging, it is strictly prohibited without exception; or
• Shipping orders with packing slips, invoices, external packaging, or other information indicating a seller name or contact information other than your own is also strictly prohibited.

Any time a customer sees packaging, invoices, or receipts identifying a seller that is not either you or Amazon it creates confusion for the customer about how their order is being fulfilled and whom they should contact with any problems or questions.

If you intend to fulfill orders using a drop shipper, you must always:

• Have an agreement with your supplier that they will identify you (and no one else) As a seller of your products on all packing slips, invoices, external packaging, and other information included or provided in connection with the products;
• Remove any packing slips, invoices, external packaging, or other information identifying a third-party drop shipper prior to shipping the order;
• Be responsible for accepting and processing customer returns of your products; and
• Comply with all other terms of your seller agreement and applicable Amazon policies.

That said, I don’t think drop-shipping from outside the UK is sensible, and as PeterB says, Alibaba sellers tend to have long lead times and large minimum order quantities.