Note that if your original degree is not BPS accredited this won't be an issue for academia, but would be a problem if you intended to pursue a professional psychology role e.g. clinical psychology, in the UK. However you would be able to (and have to) do a conversion masters in the UK that is BPS accredited and meets the requirements for the graduate basis for chartered membership (GBC). If you are planning to work outside of the UK it's entirely at the discretion of the jurisdiction you end up working in.