Help with learning about Gilt and its tax advantages

Hi everyone, long time lurker here.

My wife and I are in our early 30s and we are lucky enough to be HENRY (combined income ~300k a year). We have a small two bedroom flat in central London, which certainly isn't big enough for a family.

We planning to buy a house in the next two years 2026-2027. We have about 200k in deposit saved up and so far it's been sitting in a few savings account.

Last week I read another thread where people were suggesting instead of savings account, buy Gilt and use its tax advantages. Incidentally, my wife had a chance to speak with a tax accountant at work who said the exact same thing. However, neither of us is from the UK and Googling how and what Gilt to buy is leading me to have more questions than answers. It seems like every Gilt-related post on reddit get very mixed answers.

So I'm wondering 1) is Gilt the right tool for our purpose (i.e. 1-2 year low risk investment)? 2) are there authoritative resources on learning about Gilt investments?

Thank you so much!