A promise by the incoming National Lottery operator to slash the price of a ticket from £2 to £1 is under review.
Allwyn has also said delayed plans for new draw-based games will impact sales and the amount of money it can give to good causes in the early part of its 10-year licence.
The holdup has been blamed on legal wrangling over the handover.
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It comes as Allwyn prepares to take over the running of the lottery on 1 February, replacing Camelot.
The firm’s recently-appointed UK boss Andria Vidler has said the group will not be able to make any of the bigger changes it had pledged to introduce until next year.
Ms Vidler, who took the helm last October, said the group was trying to ensure that money for good causes will not go “backwards” this year, but that this funding was directly affected by sales growth.
She said players would not notice any “Big Bang changes” from day one, adding that the delays to new games were a “consequence of the legal issues”.
It follows delays to a planned switchover to a new technology provider after Allwyn agreed to extend the contract for existing supplier, International Games Technology (IGT).
IGT had challenged the Gambling Commission’s decision to award Allwyn the 10-year licence in court, but later dropped the legal action.
There was also a fierce legal battle with outgoing operator Camelot over the commission’s decision to award the licence to Allwyn, which was finally settled in February last year when Allwyn bought Camelot, although the two companies have since been continuing to operate separately.
Ms Vidler said: “Until all of these big challenges were resolved, we couldn’t get going.
“The challenges delayed the final award of the licence to Allwyn, which shortened the transition period.”
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The handover on 1 February marks the first time the lottery has changed hands since it was launched nearly 30 years ago.
Ms Vidler said the firm was still committed to its long-term goal to double money for good causes, but that it was set to fall short of early years targets.
On the holdup to its plans, Ms Vidler said: “Of course, Allwyn as a group is disappointed.
“There’s been a lot of frustration with constant delays, but collectively we have got 10 years, it’s not something that will happen week one or day one.”
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Ms Vidler, a former boss of music label EMI in the UK and Ireland and an ex board director at William Hill owner 888, said players would see gradual changes put in place over the next year.
This will include a limit on how many scratch cards can be bought in shops and online.
There will also be an overhaul of the lottery’s retail terminals over the year ahead, with plans to launch a trial with a small number of retailers in February, before a wider rollout.