People searching for how to buy Gilts is one of the most popular pages on Good Money Guide at the moment. We have a full guide where you can compare the best investment platforms for buying Gilts in the UK here: https://goodmoneyguide.com/investing/where-can-i-buy-uk-government-gilts/
However, to answer your question well we sourced an expert comment from Mark Glowery from Allia C&C, and author of The Sterling Bonds and Fixed Income Handbook: A practical guide for investors and advisers, who had this to say:
With higher rates on the table (currently up to 5.3% in long-dated gilts) investing in gilts and bills has become much more popular with investors. Higher-rate tax payers are also attracted by the tax-free gains offered by low-coupon gilts.
Most of the wealth management and execution-only platforms will be able to offer dealing and custody in gilts, but it is important to choose a reliable provider that can provide the service at a reasonable price.
The three major private investor platforms in the UK are Hargreaves Lansdown, ii and AJB, all of whom provide a gilt execution service across a variety of investment account types (ISA/SIPP etc.) Online execution is possible with all three with Hl and ii offering instant online dealing on live prices.
Commissions and custody rates will vary across the platforms and I would recommend modelling such charges (both dealing and custody) against your likely activity over the next few years to identify the best value provider.