I agree with whatever, it is your company, not someone elses and you should be able to make your own unique welcome e-mail.
It is true that a welcome e-mail must contain this, this and that, however it should be you wording it and so on. On to that, all programs that you use for billing and so on always give welcome e-mail templates.
You can either do it yourself, or get your solicitor to do it. True, it probably isn't something he normally does - but trust me, if you pay him, he'll do it no questions asked and do it the best he can.
Otherwise, use your brain to do it how you think it should be done. Think of what to include, word it professional, and so on.
Don't include too much information, don't include too little.
Remember, nothing more than what is needed but nothing less - the key to balance.
Another thing in the welcome e-mail, maybe just give them their username and password but make an on-line tutorial for logging into cPanel, FTP, etc. so you don't have to include the same old thing in every welcome e-mail and so you can keep it short.
However, remember to link to that on-line introductory tutorial!