The conversion from Mk2 Ph1 to Mk2 Ph2 Rear clusters is relatively easy, its simply a case of 2 of the lights being the wrong way round, snip the positive going to both and swap em round IIRC. No more than a 10minute job with a soldering Iron and some Heat Shrink and would make the biggest improvement to the car (IMO)
As you are on a budget my sudgestion would be to focus on the cheaper mods but do them correctly, for example When I started on my clio 5 years ago I wasted so much money just getting a temporary exhaust or temporary springs or w/e now I wish i'd waited and spent the extra money and just got the best from the start but I guess we all learn from our mistakes.
Now get rid of that rear cluster and get some ph2 in there
Cheep mods u could do for now.
Lose the rear wiper. £0.00
-60mm springs ~£50.00 on fleabay.
Clear side repeaters £5er from a scrappy.
Other thing I would do is take the plastic parts off and give a go @ spraying them, what's the worst that could happen u need to visit the scrappy and replace them for £5
just make sure you take the time with Prep work, the finish is ALL about the prep.
Regards Dean0