Cash-back mortgages are often aimed at first time buyers and the mortgage lender will offer a lump sum of cash at the start or sometimes at an agreed point during the term of the mortgage.
Usually the cash-back is offered as a package of benefits (e.g. linked with a discount) but pure cash-back mortgages are not uncommon.
Mortgage lenders may offer a sum of money towards the cost of legal fees or survey charges. This could be, for example, £200 to £1000 as a flat amount, or a percentage of the mortgage loan.