Non resident selling uk house

[Jessi123456]

Hi. We came to UK in 2007 all the time working. In August 2013 we bought a house for 110000. August 2015 we did remortage, house value was 125000. In July 2016 my husband living Uk abroad temprorary (looking after dad, unpayed 1 year holiday in Uk job, new full time job abroad), me and kids going abroad end of July 2016. We keep our Uk home as our intention was to back to Uk. I'm self emplyed here and coming to Uk from time to time to do a work (last tax year it was 134 days). We rent a flat abroad. Becouse dad is still not well we decide to stay abroad and want to sell our UK house.We have accepted offer for 150000.
How do we go about all this?

1. Are we qualify for Capital Gain Tax Relief?
2. Are we treated as non Uk resident? If, so this just consider as the last year.Would that mean the tax is divided by years or we pay tax gain for whole 4 years?
3. The valuation made by bank in 08.2015 can be treated as a market value for 05.04.2015 as the rules has change April 2015.
4. If we don't sell a house now how we can work it out, so the tax gain felief can be obatained in near future for example- my wife spending more days working in UK this tax year.

Kind regards