This page contains resources that I use for flight planning purposes. It is primarily put here for my own reference although I would be delighted if you find these helpful.
AIP and other administrative information
UK AIP
SPAIN AIP
PORTUGAL AIP
Portugal VFR Manual
Air Navigation Inter-Site Acronym List
IFR
EuroControl Network Operations Portal (FPL validation: Flight Planning > Structured Editor)
AUGUR GNSS Performances Prediction Tool
Auto Router
Weather
Met Office Aviation Briefing Service
WeatherWebDotNet (Simon Keeling) – models, charts, radar
ECMWF Charts
GRAMET
Windy
RASP (gliding): Regional Atmospheric Soaring Prediction
NOTAM
UK NATS NOTAM (official)
NOTAM info UK map
Flight Plan
UK NATS AFPEx Login
Spain Icaro login
Blank ICAO flight plan form (PDF)
GAR, Immigration, Customs
UK Submit GAR
ICAO Annex 9 General Declaration PDF DOC