Chill out a bit, HD! When I learned to fly the rules were thoroughly confusing - and there weren't nearly so many in those days.
n.dave, as you've already learned, we don't do VFR at night in the UK (although that may change shortly as we get common rules across Europe). But here's a quick summary of the rules today as I recall them - if you fly outside controlled airspace below 3000ft amsl, remain clear of cloud and in sight of the surface you are complying with the IFR...whilst flying around just as you would in daylight. Go above 3000ft and you have to fly at quadrantal levels but I think that's the only extra rule).
In theory, SVFR is intended to enable aircraft to take off and land in a CTZ without having to comply with IFR and you shouldn't get a SVFR transit clearance - so it would probably be best to plan your route to stay outside CAS.
A flight plan for the flight should be straightforward - you'll file a cruising level and your route will be DCT (direct) or via any navaids or positions that you choose to use. I've no idea how flight plans get filed in practice these days - it's all changed since I had anything to do with such things! You would probably do well to find a friendly instructor to take you through completing the plan and filing it - or, if there's anyone in the Briefing Room or whatever at Liverpool, speak to them about the process. Pick your time well and be honest about your level of knowledge - with a bit of luck they'll be happy to talk you through it and answer your questions. None of it is rocket science but it's all a bit daunting at first.
The above is all done from memory so I apologise now if any details are wrong but I think it broadly sums up most GA night flying in the UK.