I'm going to mention this because I can actually compare I think and help, as I too will have only 1 years NCB. I'm only 19 though. Elephant gave me an online quote for April (NCB) of £1260 TPFT for an Almera GTi up to 8000miles a year with commuting. This was paid annually; monthly I'd expect it to increase to £1400ish.
You're 21, and probably being driving longer than my 2 years, so I'd say a grands a good estimate. Maybe even under if you shop around.