Sally
Your best option would be your parents Home Insurance. Home Insurance covers the Insured and members of their family who normally reside with them. So if you have moved in you will be ok.
So you should ask nicely for your parents to increase their Home Insurance to cover your possessions, in storage at their address. You will not be able to cover the Contents at various friends addressess, so either consider self storage or ask your parents if they can store. In self storage your parents Home Insurers can arrange cover or use the storers Insurance.
In regard to your possessions you will take with you abroad, take out long-stay travel Insurance to cover these and emergency medical cover etc. As the possessions cover under Travel Insurance is limited, you may be able to obtain cover under your parents Contents Insurance. Under that policy, you would need Personal Belongings Insurance, which may be extended to cover the 8 months at extra cost. Normally personal Belongings is restricted to cover up to 30 days, but for an additional premium Insurers may be willing to extend. If such an extenstion in cover, goes over the renewal period, your parents would need to be careful to renew this cover for the relevant period.
Your parents should be aware that if you claimed under their policy, this could affect their premiums.
In regard to long stay travel Insurance, you can obtain quotes via this site http://www.moneysupermarket.com/travelinsurance/ . Be careful if you are returning to the UK periodically, as these policies only permit a certain number of returns to the UK. Long stay may not be the option if you are never away for more than 30 days. Then have a look at annual travel insurance to see whether this would suit your requirements.
Huckster