would it be better to land with cheque in striling and then change it in canada bank as i dont have a bank account in canada and was going to open one with my cheque

Only if you want to give a bank a gargantuan piece of it.
They generally give poor rates and charge commission for the privilege.

Ive not exchanged my currency yet but my research suggests there are companies that specialise in currency trading that will save you potentially several thousand bucks.
Use the search function on the forum.
www.forex.com is an example.

I opened a bank account in NS while on recce with my passport and deposited 20 bucks. When I am ready I will transfer the rest in chunks to £1000 then £5000 and higher. I will do this so I dont lose it all if the first one goes wrong. I am probably being paranoid becuase it seems loads of folks on the site have transferred money quite successfully this way.
If you are with HSBC I understand its a formality for them to open a Canadian account for you then there is no fees to exchange. Or so I hear. You need to DYOR.

If you deposit a cheque drawn on a bank outside Canada they might hold the funds for a long time, 30 days or so, so make sure you have access to other funds to keep you going until then.

It don't work that way. There's no reason why you can't open a Canadian account before you get here and then use a wire transfer or a specialist company to do the transaction. You'll save many percentage points over bring a personal draft in the luggage.

Striling?

You can write yourself a cheque drawn on your UK bank account and deposit it in a $CDN account. As has been said, be prepared for a holding period though until the cheque is cleared. Wire transfer will cost more for the transaction, however the funds are available more readily. Once you have established a history with a bank there may be no holding period on FX.

An FX house may give a better rate, but not always. Custom House Exchange are a Canadian FX house with offices in the UK.

The larger the sum, in general the better rate you will get. Bringing over small chunks spreads the risk if the rate improves while you are exchanging. However if it goes down you lose. A deposit of £5000 for example will unlikely get you a very good rate when compared to £100,000+.