Hi. My name is*****'m looking at your question now and will post my answer or ask for more information here in a short while.
I can only deal with the UK tax implications of your question. You would need to seek local advice as to the German tax implications of a gift of a UK property.
If you gave the UK property to your wife there would be no gain or loss as transfers of assets between the parties to a marriage are tax neutral in the UK as far as Capital Gains Tax is concerned. As your wife is an EU national, she would be entitled to a UK personal allowance to offset against the rental income. See Box 16 here on page RRN5 here. As your wife is non-UK domiciled, the intra-spouse gift rules for Inheritance Tax purposes are diffferent to those where both spouses are UK domiciled as you can read here.
If you gifted the property to your children, that would constitute a disposal for Capital Gains Tax purposes and you may have to pay CGT depending on how you choose to calculate the gain as a non-UK resident. See here and here for more information. It would also be a gift for Inheritance Tax purposes which would rermain in your estate for seven years after it is made. See here for more information. If you are UK domiciled, your worldwide estate is liable to UK IHT whereas if you are not UK domiciled, only your UK based estate is liable to UK IHT. See section 5 of RDR1 here.
I hope this helps but let me know if you have any further questions.
1 I cannot refer across to another just answer section I'm afraid.
2 As your children are EU nationals and have British nationality in any event, they will qualify for the UK personal allowance.
3 Domicile is a difficult concept. You do have a UK pension which is taxed there and you have a UK rental property. However, given that your life seems to be based in Germany, you have a case for arguing that you are no longer UK domiciled. There are some more notes here.