I think the next review is supposed to be at the end of May so it is possible the rules might change then. I think the tourist minister has made it clear he wants UK tourists here but I suspect that people in government who are concentrating on the public health side of the debate will not want to include the UK as long as the number of new cases per day stays high. Which side will win? Who knows?
The UK has managed to focus everybody's attention on the R number but it is not the only important parameter. If you only concentrate on the R number you could argue that the UK is doing better than Greece, because in the UK the number of new cases per day is going down, i.e. R less than 1, whereas in Greece they are roughly constant, i.e. R = 1 approximately. The difference is that the UK still has over 2,000 new cases per day while Greece has in the region of 10 new cases per day. If you look on the Worldometers web site
you will find that the worst performing country on the list of allowed countries, in terms of new cases per day, is Poland which is just under 400. On the other hand Poland has had a very low death rate at 26 per million population and a low overall infection rate of 563 per million population. I have no knowledge about how the Greek government is making its decisions on which countries to allow entry would guess that the Greek government is calculating some sort of score based on those three parameters. If I am correct the UK, with a death rate of 542 per million population and an overall infection rate of 3,825 cases per million population, is going to have to get its new case count very low to be considered. I may well be wrong.