Most of it is fine. There are only a few things which need clearing up. 1) Use "three of my friends" or "three friends of mine". "Three my friends" is completely wrong. 2) I'm not sure about the use of "I have booked". By itself it looks fine, but in context (when you went on to describe your time in Stratford-upon-Avon) it is wrong. You need past tenses only. 5) Your first sentence is correct: "...stopping every now and again to take short walks". If you used "taking", the sentence would become broken English.

Your sentences are really good! Here are a few suggestions: 1) You can either say "three friends of mine" OR "three of my friends" 2) I think it would be better to use "ago, so" instead of "ago and". 3) "Then" and "our" are unnecessary. You can say "all we wanted to do was to have a good meal and go to bed." 4) I don't think you need to use "quite," but you can. You could also use "rather." 5) I would say "take a short walk" or simply "explore." Really, though. Great job :)

1) Last week I spent a most enjoyable few days in Stratford-upon-Avon with three my friends (maybe "friends of mine" souds better?) Last week, I enjoyed a few days in Stratford-upon-Avon with my three friends. (Direct sentences are often easier to understand.) 2) We decided to go several weeks ago and I have booked rooms for the four of us at a hotel in the town. We decided to go, several weeks ago, so I booked rooms for us at a local hotel. (Inserting commas around time makes it easier to read. The words following "so" give the reason why you booked the rooms. You could also substitute "therefore". The sentence would then read "We decided to go, several weeks ago, therefore I booked rooms for us at at a local hotel." 3)The hotel was really impressive on the outside but the bedrooms were rather small. We arrived quite late on the first evening as we had been working during the whole day and all we wanted to do then was to have a good meal and go to our beds The hotel was really impressive outside but the bedrooms were rather small. We arrived quite late since we worked all day so all we wanted to do was to have a good meal and go to bed. (Again, try to be short and sweet. Your meaning will often be clearer.) 4)The following morning we got up quite late and had a large breakfast in the hotel. Great as is! 5)We spent the rest of the day driving around the countryside, stopping every now and again to take short walks. (or i should say "taking short walks"?) We spent the rest of the day driving around the countryside, stopping every now and then to take short walks. (In American English, the phrase is "now and then").