If you just want to know where you are, then
UK AirspaceAVOID by PocketFMS will do the job for free. It doesn't allow flight planning. It just shows where you are relative to airspace and warns if you are about to enter.
Couldn't be simpler, nor cheaper! And it's NATS approved.
If you want something more advanced, then try
EasyVFR by PocketFMS.
€69.99 for an annual subscription on one operating system including advanced weather, NOTAM, and aerodata updates or €150 for all operating systems.
PocketFMS are the original developers of mobile aviation moving map software for consumer devices. It's being going for over 11 years now.