I've got a lovely pair of lightweight jods by John McDougall that I bought from my local tack shop and I think you can get summer weight jods from Robinsons although don't know what brands they have
I have a lovely pair of Gallop denim jean/jods in dark blue with lycra. They have jean style bottoms and you can almost get away with them as normal jeans to go shopping. Got them on Ebay really cheap £22.
They are lovely to ride in and thick enough to stops the clegs biting through to the flesh. ( a very important feature IMO)
My other favourite summer breeches are Eurostar Starts, comfortable and thin and make you look a nice shape.
Only suitable for windy days in summer though, otherwise clegs bite through them (see above).