Your bill shows your base plan or add-on cost, promo discounts if applicable, VAT at 20%, and your total.
International calls and premium SMS are charged separately as you use them — they're not part of your monthly plan.
You invoices will show:
Bill Period: The timeframe your payment covers (typically from signup/renewal date to the same date next month)
Subtotal: Your SIM plan cost before VAT
VAT: Value Added Tax (currently 20% in the UK)
Total: Subtotal plus VAT
You receive a bill every month.