Hi ebe,

With your goal of low risk and tax-free saving, products from National Savings & Investments are an option (nsandi.com). It offers fixed-interest and index-linked savings certificates that are tax-free. The downside of these however is that the minimum term is two-years and the rates aren't fantastic.

An offset mortgage is certainly another option, where the advantage is that while you won’t earn any interest on your savings, you pay less interest on your mortgage and shorten its term - while maintaining easy access to your money. The savings can be quite attractive, for example - a higher-rate taxpayer with a£150,000 mortgage over a 25-year term and just £5,000 in savings could save£7,817 more through offsetting this compared to the interest they would earn in asavings account.

This example uses Melton Mowbray Building Society’s lifetimeoffset tracker, currently at 5.74%, and Kaupthing Edge’s instant accesssavings account, paying 6.5%. Not only would you save almost £8,000, you could also become mortgage free one year and nine months earlier.

You don't mention whether you are saving into a pension. While this is long-term saving that you can't access until retirement, there a big tax advantages and it should form part of your financial planning for the future.

Hope that helps!