I do not believe that a CW3000 is a good investment. It is just a radiator and fan so it can't cool any lower than ambient temperature. If your are going to invest in a chiller, wait until you can afford a bit more for a CW5000. Quality 80W tube makers require a CW5000 or better for warranty. 3000 won't qualify.
My 80W shipped with the pump to use with a water bucket even though it was not warranty compliant for my EFR tube. While waiting for an exchange of my damaged first cw5000, I tried the pump+bucket or water+frozen jugs of water. During the cooler months here in the USA I probably would have been OK but at the end of a long hot summer I was going through ice faster than I could freeze it. A lot will depend on your UK location's weather, how often you use it and how long your sessions last. I am glad I bit the bullet and invested in the cw5000. It is ready to go as soon as my laser boots up and it monitors the water better than I have time to do correctly.
Make sure you are getting a genuine S&A chiller. Lots of fakes out there. I know your are in the UK, but in the end for me here in the USA, ordering direct from China was better than ordering from a seller with units stored in California. It was cheaper, arrived in less time via air freight and wasn't damaged by UPS like the California unit I initially bought.