If you have a longer haired dog you may need to pay for grooming too. We pay about 50 quid every 4-6 months for two Spaniels
You will also needs vaccinations and boosters
As far as insurance goes, I pay about 40/ month (2 dogs) which sounds a lot but after heart problems (cocker), grass seeds (both), and a few other issues, we have had more out than we have put in!
You will also need to pay for kennels if you are away. (or have understanding family) We never leave ours for more than 4-5 hours so if we are out for the day we make sure someone comes and looks in on the dogs for us. Lots of things to consider
Its worth every penny