Campervan wifi / 5g signal

[Gman1]

Does anybody know off affordable way of improving wifi/4or5 g signal without spending fortune and running cables everywhere and drilling holes in van.

It really depends on where you are in the country and if there’s a mobile mast nearby which is supplying your provider (EE, Voda etc). Lookup Cellmapper.net for their coverage map of the UK.

Ask on this specialist forum…

https://www.ispreview.co.uk/talk/forums/mobile-broadband-and-fixed-wireless.106/

A booster can only work with what is there - so if you are remote and signal poor, even a mast and 'posh' set up will have limitations.
Many sites have wifi now across a lot of the site.
I take a good book and jigsaw puzzle in case.