I have taken a slight liberty calling English Lavender (Lavendula augustifolia) British, which it surely must be.
Other Lavenders will grow and thrive in the UK including French and Spanish Lavender but they will last only a few years whilst English Lavender can live for 20+ years.

English Lavender (Lavendula augustifolia)

• Varieties to look for include Imperial Gem, Hidcote and Munstead which have a compact habit and Melissa Lilac.
• These British Lavender flowers in early summer on short flower spikes a few inches above narrow, grey-green leaves.
• In August the flowers will be virtually over and the plant can be trimmed back hard so they regenerate before winter
• Cut flowers for drying in late June and early July

You can acquire or just admire plants as part of a collection

Spanish Lavender

Growing Tips for Lavender

• Water in the first season so the Lavender can develop deep roots then in future years they can survive on very little water.
• The silvery aromatic leaves indicate that Lavender prefers full sun and good drainage like similar plants.
• The tufted French and Spanish lavenders are variable in habit and flowering colour.
• Buy plants from a good nursery who will have a stock of varieties.
• Grow Lavender from cuttings from May to August

Commercially Grown English Lavender

Lavandins are Lavandula X intermedia and they can be clipped to produce roundels or cloud shaped plants.
Lavender is a top plant for nectar and Butterflies love British Lavender

Photo credits
Lavender by Mrs Magic CC BY-NC-SA 2.0
Lavender by Zombie Normal CC BY-NC 2.0
Lavender by amandabhslater CC BY-SA 2.0