decent stoves start around £600 to £650 and climb to easily double that for some. If your chimney is sound then a short length of viscous enamel pipe, a register plate and sundries to connect cost about £50. If chimney needs lining then add another £300ish for a good liner and cap. Hearth cost depends if its a few clay tiles, or a large granite slab. Fitting, including opening up the fireplace, I'd guess most places will do it in 2 days work. One day maybe if they don't line the flue and its all straight forward. If lining flue they may need scaffolding to access the stack. £2.5K plus or minus £500 is probably a ball park guide.
Stovax stockton 5 here.