The Eurostar comes in both microlight and SEP versions which are identical apart from the latter having an electric fuel pump. So you can do an NPPL (SSEA) in a Eurostar or an NPPL (M). The former will allow you fly larger aircraft such as the PA-28 and C 172 after type conversion, or even a Chipmunk, but no night/IMC add on ratings - its all gotta be day VFR.
The NPPL(M) limits you to other Eurostar type 3 axis aircraft or should you wish a flex wing - again after conversion.
Its not an easy decision. If you want to enjoy the sheer pleasure of flying with one other person and see the ground below you then a NPPL(M) is for you. Google image WT9 Dynamic - you could fly one of those for example.
If you must carry more than one passenger or fly taildraggers or do aerobatics then its NPPL(SSEA)
If its the above plus sub VFR weather flying (you may not necessarily see the ground) or night flying then its JAR PPL (A)
You must also have a plan for financing your post licence flying. Research the cost of a half day hire to Sywell in a Eurostar vs a IFR equipped PA-28/c172 type !!!
I can only speak personally but don't assume you can always get 2 or 3 friends to share a 4 seater costs. In reality after initial enthusiasm interest wanes and so this rarely is the case and you will end up paying top dollar for seats you don't need.
You then look with envy at the Eurostar pilots paying around half the rental compared to your 4 seater.
FS