Oliver,
Happy birthday my friend!
As to light weight amps/cabs ....
I've been using Genz Benz stuff now for about a year. The bad news is Fender, in its infinite wisdom shut them down a little while ago. It would be tough for you to find stuff brand new anymore, though there is some still out there (Bass Central has some heads left).
Mark Bass is one line you might want to look at, as well as Gallien Krueger's MB series. If you can find Genz Benz, you can get a Shuttle Max 9.2 or 12.2 head that weighs about 6.5 pounds. The Shuttle cabs, if you can find them are usually around 40-50 lbs. My Shuttle 6.2/2X10 rig weighs a total of 43 pounds, for example, with 375 watts at 8 ohms, and 600 at 4 ohms, all with a tube preamp section. It's plenty loud, lots of head room, and relatively light.
Euphonic Audio is another brand you might want to look into for lightweight stuff. Their heads are solid state, but are light and powerful, as are their cabinets. Finally, there's the Ampeg PF series with light cabs and heads.
Hope this helps,
Alan