Bed and ISA Bitcoin to ISA ETF

I’m looking to reduce exposure to btc gradually over the next few years and reduce capital gains tax ahead of potentially buying a house in 5 or so years time. My plan is to sell 3k of btc each tax year (to the CGT allowance) and reinvest in S&S Isa or Cash Isa. I believe btc is a little under valued at the moment and i would rather DCA as opposed to sell in one go. Is it acceptable, from a tax perspective, to sell 3k in btc, deposit the 3k in the S&S ISA in a bitcoin ETF such as Ishares physical BTC. Then over a year convert the funds in the ETF into something like the FTSE all world? Would those funds no longer be subject to capital gains since im reinvesting in a different instrument and in an isa?