Very much belated, but thank you for all your above advice. After a month or two of toing and froing I decided to opt for the 80ED on an AZ5 manual mount. It took me a couple of months to pick up all the bits second hand (aside from a few eyepieces) but I got there eventually! Here's what I bought for circa £750:
- Skywatcher 80ED pro kit
- AZ5 Mount
- Skywatcher Steel 3/8" tripod
- AZ5 extension pillar
- BST Starguiders 5mm, 8mm & 15mm
- Baader Classic Ortho 6mm & 10mm.
Thanks to the clouds (!!!) I've only had it out a couple of times, but I've had some amazing views of the moon and I think I saw M57 (ring nebula). In a word, I'm hooked! Looking to add a 4mm planetary eyepiece (Vixen SLV or OVL Nirvana) and a 18mm Classic Ortho too as I love the view through the 6mm & 10mm classic orthos.
Thanks again!