Can any one recommend a car rental company they have used in England and/or Ireland. We will be in Wales for one week, flying in from Heathrow, then Ireland (perhaps taking the ferry from Wales to Ireland) then to Cornwall England for a week. For June 21 thru July 10! Please help!

Start with autoeurope.com.

I assume you mean separate rentals - since typically car rental agencies will not allow you to take them on ferries to other countries.

We always use Hertz - but have a special corporate discount.

I used Hertz last year and it was fine (picked up in Edinburgh drop at LHR.) I've also used Europcar, although not in the UK, and it was always fine as well.

There are rental companies that allow you to take a UK rented car onto a ferry and to take it abroad, Hertz being one of them. Use a company such as Autoeurope and ask about it when you make the reservation as there might be a charge and/or restrictions. Or check the rental companies own website for further info.

Thrifty.

Seriously, use Europcar or an American company (if you're American) so that you can hold the company accountable later - i.e., you can ream out Hertz/Thrifty/Budget for cruddy service if that's what you get.

Autoeurope is a consolidator. That doesn't mean don't use them, it means that renting through it is similar to rentalcars.com.

Personally I tire of the rubbish put about in respect of Irish car hire... http://goo.gl/NswqEj

Booking thru a consolidator is not an issue. The booking is still made with a major car rental company. It all ends up in the same reservation system but with a less expensive price. You pay for the same insurance cover. You still get asked when you pick up the car if you want additional insurance to cover the excess (deductible) if there is one. If there is an issue, it makes no difference how it was booked. The rental contract you sign when you pick the car up, is the rental company's one.

I presume you have a reason for travelling to Ireland in the middle of your visit to England/Wales

In any case it doesn't really affect the answer that you have a car in England/Wales and a separate one for Ireland as the ferry costs and out of country usage costs will be extremely high

You will also find getting to Cornwall from Ireland difficult as there are no direct routes

Ideally you would either fly to London, travel to Cornwall then Wales, cross the Irish Sea to visit Ireland then return home - or the reverse. You seem to have picked the worst combination

Also do get a night's sleep when you arrive before picking up a car

The continental surcharge is clearly mentioned on the Hertz website (as an example), the cost is not prohibitive as the cost of a new car rental might not be that much cheaper. I've taken rental cars to other countries and have put my rental car on a ferry. The rental company will have a list of allowed countries and authorised car groups posted on their website and then you can decide if the driving abroad fee is worth it.

I wish people who have never rented a car in Ireland in person and people who work for Agents/Consolidators would stay away from advising the finer detail of things they know nothing about..

In respect of taking a car between the two Islands.. Some companies allow this.. Should I say the insurance underwriters for some Insurance companies allow this.. The cost of additional Insurance (which does not cover time at sea on the ferry) and recovery insurance can be prohibitive.. shop around direct with the companies who will hand over the keys for your chosen car, They are best placed to give the at the collection desk price especially on such a complex two location requirement..
If you decide to use Stena Line ferry send me a private message for some information might be able to save you a little on the €400+ ferry fare..

Over many years and many, many rentals I have consistently never had an issue with AE, their deals are extremely good.

I am resident in the UK and have rented over the world. Never in the UK, so my logic may not apply in your case.