The brand of the amp is not too important, if you can try it out in a shop and check the sound is okay then that is great. I would be fussier about the guitar than the amp at the start. But at least check out some reviews of the amp brand to ensure they are reasonable quality.
Go for an electronic amp at the start rather a tube amp, will be cheaper and more robust. If it has a built in overdrive or distortion (or reverb) this will save you a few quid. You will not need to get pedals right away as the built in effect will give you a good sound to practise.
Also spend at least $20 or more on your guitar lead or cable. Get a good quality thick one. Don't get a really long one, 2 or 3 meters long will do. Longer ones (5 0r 10 meters) cause more signal loss and noise. Cheaper ones don't last and can cause unwanted noise especially before they begin to fail. Not all noise in rock is good.
Powering up with an amp will open up a whole new world for your rock guitar playing.