Hi dearg,
Taxes and fees combined should be between 5.5 and 10% of the value of the property. All of these fees are combined together as "Frais Notaires". The reason for the large spread in % is that part of the taxes is a mortgage tax which depends on the amount of mortgage registered against the property. If you are financing the purchase through a remortgage of property in Ireland the French will just view this as paying cash, as the mortgage tax only applies to mortgages registered against the French property.
With renovations etc in Brittany, check out
www.angloinfo.com, due to the number of ex-pats living in France there is a mini industry of Irish, English and english-speaking builders etc to service the market. They tend to charge a premium for their services, but then again a lot of French builders will just take the mick out of a foreigner anyway. Ask for references before you commit to any builder over there.
Re extensions, all houses in France have what is known as a "cos". This is the exact size a house is allowed to be on a plot of land. So even though you may have the space to extend, you may not be allowed to. It's best to speak to the local agent when you view the property, and then talk to a local architect. All planning is handled through the local town hall, and even the smallest villages have their own town hall and Mayor.
France Telecom do combined tv, broadband and phone packages for 29.90 a month, if you want to get English TV it will cost your about 400 Euro for a dish and a sky box with various packages. As French TV will make your ears bleed and will leave you crying yourself to sleep at night, you might want to consider the 2nd option.
The two main taxes you will pay are Tax Foncier and Taxe d'Habitation, these are both set annually by the local town hall and vary from town to town and property to property. Ask the agent when you are viewing the property what the taxes and charges are.
Finally as regards buying the property, you will be much better off if you don't do it remotely. Pick an area, spend a couple of weeks bumbling around on holiday and go into the local agencies.