It's always best to have a completely clear subfloor void with plenty of unobstructed air-bricks for ventilation. As mentioned, ours were all filled to the brim with shite, all air-bricks blocked.
Yeah makes sense, if it was that full under there I'd do the same. I don't think it is that bad, based on peering through the one loose "access" floorboard we have in the hall, so the crawl method is probably open to me (whether I should be happy about that or not is another question)
It's always best to have a completely clear subfloor void with plenty of unobstructed air-bricks for ventilation. As mentioned, ours were all filled to the brim with shite, all air-bricks blocked.