Assuming they haven't already done so (lets not rule that out given all the sell-on-any-news since Feb), £500,000 would take about a week on current traded volume.
PXEN has the same auction timings as every other shares traded on the SETSqx trading system. Along with the closing auction, there are three other intra-day auctions that take place during every trading day:
If as you say, the Tesorillo area is full of eco-hippies, then they must be fuming that the Maghreb–Europe gas pipeline comes ashore less than 3km from the wellsite, and runs right through the block.
Getting a gas sales agreement for Italy in place would be a nice start. Spain will chug along regardless and obviously has significant further upside potential, but Italy 1st gas sales is the main prize this year.