One-way Heathrow-Faro flights with British Airways are available from £273 on 15 May, two days before the expected resumption of non-essential international travel. Two days later, the flights on the same route cost from £565.
Ryanair, meanwhile, is selling Stansted-Lisbon flights for £128 on 14 May, rising to £262 on 19 May.
Flight prices do, however, drop considerably over the weeks following the proposed restart. TTG was able to find June flights to Portugal for as low as £19.
It should be noted the government is yet to formally confirm the current ban on all non-essential international travel will be lifted from 17 May.