The advantage of being a first time buyer is that you are not liable to pay stamp duty on any purchase up to the value of £425,000, any purchase over that is subject to a 5% charge on the amount in excess of £425,000, and any purchase over £625,000 for a first time buyer is not exempt and will be subject to normal stamp duty rates. For couples purchasing their first home together, stamp duty would still be payable if one party has owned a property before, even if the other person has not.
There are also government schemes and preferential mortgage products for first time buyers. For instance, the First Homes scheme provides a 30-50% discount on eligible properties, while a lot of mortgage lenders have specific FTB products some of which allow customers to pay as little as 5% deposit, all of which means that purchasing a property can be a lot more affordable for first time buyers and makes the process a lot less daunting.