Lloyd - you're clearly getting some light to the ground, so thats a good start.
I'd be tempted to go in and open up some small coppice coupes - maybe 10m square, and get the old coppice stools back to production/growth
then clear out a stalking path between them that takes you close enough to see and fire into the coupe without walking into it, thin the trees to give you a clean firing line.
read this:
http://www.forestry.gov.uk/pdf/fcpn6.pdf/$file/fcpn6.pdf
It depends how much time you've got and how far you want to go
doesn't take long to turn
into
without having to cut down any big trees at all.