Ah. Now we get the full assignment!
Aldeburgh; taxi, own car, or hire car to Woodbridge (assuming you have PPR); fly Woodbridge to Welshpool; hire car from Welshpool to Llanuwchllyn (note the spelling there!).
There is no car hire firm at Welshpool, so negotiation will be needed. Ditto Woodbridge (but maybe you could arrange for the Distaff Side to drive the WC mobile from Aldeburgh to Wbr, and/or from Wbr home).
If there's no negotiable hire car at Woodbridge or Welshpool, you need to renegotiate with the religious camp.
If Woodbridge is out, maybe Crowfield or another of those fine ex-WW2 airfields?
I never had such problems with religious camps - are you sure you're negotiating with the right person? I've always found them very accommodating and happy to go along with whatever plan I suggest. Do you need me to have a word with the "authorities" there on your behalf (are they of the appropriate persuasion)?
I'd reckon Aldeburgh to Llanuwchllyn by car is at least 5 hours on a summer Sunday, especially given that Suffolk is involved. Even with a good run up the A14 it's going to be exciting.