The Flight School at Reykjavik is very friendly. Plenty of reasonably equipped 172s and similar available for hire at rates not dissimilar to the UK.
Weather is your biggest risk at any time of year. When the clouds and fog decide to settle, they can stay for days on end, wrecking the best of plans.
Airspace is pretty straightforward as is ATC, with only the odd US-style oddity to get used to (1200 instead of 7000 for example)