Enzo,
Firstly, the Nationwide is the UK’s largest building society and if the proposed takeovers of the Cheshire BS and Derbyshire BS by the Nationwide are approved by the financial regulators, the Nationwide will have almost 15 million members, 1,000 retail outlets, £191 billion assets and £122 billion of retail deposits.
Our advice to savers this week has been not to keep more than £35,000 with one particular savings institution. The Financial Services Compensation Scheme covers 100% of the first £35,000, per person, per deposit taking institution. So if you want to be cautious don't have more than £35,000 with any one savings provider, if in the unlikely event the worst should happen, you will get all your money back.
If you’re being ultra cautious you do also need to consider which savings account providers are registered under one banking licence, otherwise your savings will only be covered once. Read our guide to who owns who and who has a banking licence for more information.
As far as I'm aware Children's savings accounts are covered under the financial services compensation scheme. If the savings account is held in the parent or guardian's name, then you might find that it's included in the parent or guardian's limit. It's probably wise to check with the Nationwide and refer to the Financial Services Compensation Scheme website for more information.
In terms of child trust funds, the Financial Services compensation scheme states that it covers deposits and investment business, however, it doesn't explicitly mention child trust funds. I would suggest that you double check with the Nationwide in the first instance.