The beaches at Welcombe Mouth and Marsland are walking distance from the house. Welcombe is the busier as it has a (small) car park but is very good for surf at low tide. Marsland is very quiet and beautiful but no surfing there as the rocks go out to sea. Sandy Mouth provides a long sandy beach at low tide but is a short drive away.
Welcombe Mouth

Welcombe Beach is a 5 minute drive from the house to the beach car park or a 25 minute walk along the road and via a footpath to the coastal path.
Marsland

Marsland beach is a beautiful walk from the house and is usually empty. It is ideal for picnicking and swimming but too rocky for surfing. At low tide, you can cross the rocks to Welcombe beach.
Sandy Mouth
If you want a huge sandy beach, drive south alongthe main road(A39) towards Bude, through Kilkhampton and right as signposted to Sandymouth. About 15 mins drive.
Walking South to Morwenstow and Bude

The walk to Morwenstow along the cliff path is worthwhile if energetic. Walk down to Marsland Mouth but just before the beach instead follow the Coastal Path south across the bridge. There are a number of deep valleys to cross en route but the views across Bude bay to Tintagel and beyond are worth the climbs out of the dips.
North to Hartland
From Welcombe Beach follow the Coastal Path north. The route gives spectacular views of Lundy Island and the dramatic cliff coast line. There are a number of options to turn off the path; at South Hole, Speke's Mill Mouth and Hartland Quay.