Going back to the OP’s conundrum, they are mortgage-clear, maxing out AVC’s, and sitting on 170k cash on deposit, with a desire to retire in 10 years at age 62.
I would consider pre-loading some AVC’s to get tax-free compounding going asap (unless buying a basket portfolio of stocks is your thing) and claim tax back in future years. The main benefit will be getting a fund/ETF-like experience without the deemed disposal nonsense that goes with it, although you will lose flexibility of having a wedge of accessible capital until you draw down your TFLS and/or restock cash pile from future tax rebates/not paying AVC’s from salary.
Marginal enough tax benefit though compared to just paying max AVC’s from salary.