Hello I am a solicitor with 20 years experience. I will try to answer this.
There is no rule against you and your father buying a place together to make your money go further. There are many different arrangements that you and your father could put in place but the only sensible way to deal with this is to discuss matters face to face with a solicitor. Most solicitors who undertake conveyancing work would be able to help. Something you may want to consider is that your father is likely to predecease you and his share in the property may well be a significant part of his estate. You might want to think carefully in advance what will happen to that upon his death.