If the car seats you are looking at say they are up to approx 15 months (will be somewhere between 75cm and 87cm limit) then it's the kind you can remove and put onto the pram. In baby shop/car seat lingo these are called "infant carriers". There are a few with 360 bases - Britax Babysense / Babysafe 3, Cybex Cloud Z and the newer version of it, Maxi Cosi Coral 360 and Pebble 360. These are all compatible with the same standard adapters that go onto all the popular brands of pram.
But - they are very pricey IMO - the car seats themselves over £200 and the bases around £200. They will tell you this is good value because the base can take a toddler seat, but beware, the toddler seats that fit into these bases cost £300 by themselves, which is on the upper end of the mid range of toddler car seat costs, and most toddler car seats don't need a separate base, they either come with the base attached or they fit using seatbelt without any base at all. All in all the total cost of the systems are over £6-700, which is a lot of money. £400+ if you just buy the baby portion which again is a lot for something that lasts around a year. You can get an infant carrier and base combination for more like £2-300 if you can do without the spinning function. Car seats do not have anywhere near the resale value of prams as people are advised not to buy second hand car seats, so spend the money if it's worth it to you - don't bank on getting any of it back later.
The seats which are 360 spin which say they are up to approx 4 years or older, don't detach to go onto a pram, they are too big/bulky. There is an exception - Recaro have a couple of models, Zero one elite and Salia elite, that have the spin base and a large seat for toddler up to approx 4 years, with a pop out carry piece for baby up to approx 6-12 months depending on how big your baby is. That can be used on a pram but you need an extra adapter to adapt the seat to the standard adapters, which might be a bit of a pain. But next to the cost of the modular sets with 2 seats 1 base, it looks quite reasonable as only costs around £400.
Otherwise if you're looking at seats 0-4 years you'll want to check how it fits in your car and see if the store have a newborn sized doll you can try in the seat. They can be tricky to get a good fit for newborns. If you're not in the car very often this might not be an issue as they soon fit better as they grow. But if you use the car a lot, an infant carrier is likely to be a better choice.
Personally I wouldn't go for the ones that are all in one up to 12 years. They just don't tend to give as much in terms of performance and flexibility as you'd hope. Better to get something tailored for each stage.
As for prams, look at the Stroller Workshop on youtube - these are a Norwegian company who fix pushchairs and they review all kinds of models for longevity and features and the likelihood that they will last you. They seem to really rate the Uppababy :)