just need it to clip on to the pram and the option to belt in as well as base
90% of infant car seats do this.
For pram compatability - essentially anything by Maxi Cosi, Cybex, Nuna, Avionaut, Joie (except Juva), Britax, or Besafe, as long as it's the infant carrier type, with a handle and sold as approx up to 15 months (Cybex say 2 years but it's the same type of seat). Plus I think Cosatto and even the newer Graco seats seem to have the same adapters now.
These brands all have the right adapters for this pram and 90% of car seats of this type can be belt fitted off the base and base fitted too. The exceptions are Joie i-Level, some of the Nuna seats, possibly a couple of the Maxi Cosi. Do double check but the vast majority can do both.
If you are planning to belt fit on a semi regular basis I would defo look at Maxi Cosi, Britax and the Avionaut Cosmo has a really nice easy belt path too. A lot of infant carrier seats these days they design the belt fitting as more of an occasional use thing and it's not so easy to use.
For me I think Cosmo probably ticks all boxes in terms of price, fit, ease of use and longevity. Britax Babysafe Core is always spoken highly of as well.