i wouldn't complicate it, do one or the other. "Know" where gold is going and trade it
fluctuations in GBPUSD wont make great difference in short term. I use ETF goldx3 leverage (Boost Gold 3x Leverage Daily ETP), however be warned, if you keep trades on for long time "fees" will eat into it, try and get in out on max weekly basis, have targets and get out, know your entry points, remember "well bought is half sold"!
Also remember, ETFs subject to trading hours and closed on US holidays, can be a bit scary if you forget..
You can do this in a SIPP or an ISA, that will give you