Hi Ben,
you sound like me 5 or so years back!
I went through BTCV and gained NVQ 1+2 alongside some volunteering for FC and a bit of working for myself in gardens/ allotments etc.
In 2007 I gained an apprenticeship with Forestry Commission working in a very similar (although MUCH less organised) fashion to BTCV, working towards NVQ3 in Trees and Timber and gaining most tickets on the way.
Its a really good scheme and one I would highly reccomend aslong as your prepared to drive it.
FC aren't really focussed on NVQ's in the way you will be used to but the support you will get combined with the experience you have makes for a solid combination aslong as you work for it.
Theres a fair bit of info on the FC website regarding the scheme and some contacts.
I'm not alltogether sure who is in charge of the scheme in Englandshire or I'd give you a name.
A lad I worked with at BTCV also went onto an apprenticeship with FC more recently after volunteering elsewhere for a while.
Not much help I know but hopefully a glimmer of light for you that your on the right track and your background has provided chances to others.
As you well kow times are hard and jobs are hard to come by but your well placed if/ when they do.
I moved to Scotland and the other lad went to Wales aswell for the apprenticeship but I know Sherwood are "looking into" apprentices so keep an eye out and maybe get in touch now, foot in the door so to speak.
I would try STEP as they work out of Stocksbridge, environmental consultancy type place.
Don't really know much about them sorry other than that they exist!
Sheffield and Derbyshire Wildlife Trusts have vacancies from time to time and have bother taken ex BTCV people that I know of, 1 of which again went onto FC apprenticeship.
Lots of conservation work on Wharncliffe Craggs as theres a SSI site.
Maybe volunteering opportunities at least if you contact them.
Groundwork Sheffield have done a fair bit of "urban regeneration" type work recently but mostly advertise volunteering positions that I have seen.
I was in touch with Heely City Farm when I moved, they weren't exactly forthcoming with jobs but quite keen and kept good contact with me, places like that are worth talking to.
Wadsley and Loxley Commoners used to do lots of volunteer path work, stone pitching, coppicing etc. which is good experience if you can get it.
Just do what you can, bang on every door you think of and it will pay off eventually.
You never know you may even become a miserable civil servant ha ha!