There are limits to the protection the FSCS provides which may vary by financial product. The FSCS protects:
Deposits up to £85,000 per person per firm.
100% of the claim with no upper limit for claims relating to long term insurance policies (such as pension and life insurance)
Investments up to a limit of £85,000 per person per firm. These include claims relating from bad investment advice, poor investment management or misrepresentation.
The compensation limit for retirement savings will depend on the exact nature of the product (or products) you buy.